1. Field of the Invention
A liquid crystal display device has no defects when aligned by using a siloxane-based alignment film.
2. Description of the Related Art
The recent development of portable electronic equipment such as mobile phones, PDAs and notebook computers have resulted in a gradual increase in the demand for light and small flat panel display devices suitable for these products. Active research covers such flat panel display devices such as liquid crystal displays (LCDs), plasma display panels (PDPs), field emission displays (FEDs) and vacuum fluorescent displays (VFDs) and the like. Especially, the LCDs are currently in the limelight due to the mass production advantages of the technology, the versatility of the technology and the high-definition quality of the display.
Liquid crystal display devices of the related art form alignment films from polyamic acid, polyimide and the like on the interior facing surfaces of two substrates. A cell with a sandwich structure forms by injecting a nematic liquid crystal layer having a dielectric anisotropy between the two substrates.
An example of a typical related art liquid crystal display device is a twisted nematic (TN) mode liquid crystal display device, where the major axis of the liquid crystal molecules in the liquid crystal layer continually twist at an angle of 90 degrees from one substrate to the other substrate.
Further, super twisted nematic (STN) mode liquid crystal display devices and in plain switching (IPS) mode liquid crystal display devices have high contrast and less optical dependency on such factors as viewing angle when compared to the TN type liquid crystal display devices. The STN mode liquid crystal display uses a material that blends a nematic type liquid crystal with a chiral component. The STN mode liquid crystal display also uses the double refraction effect generated by the consecutive twist of more than 180 degrees by the major axis of the liquid crystal molecules between the upper substrate and the lower substrate.
These displays require various forms of liquid crystal alignment that can be achieved by rubbing the liquid crystal alignment film.
However, rubbing the liquid crystal alignment film is generally carried out by the process of scrubbing the alignment film with fabric. Thus, static electricity easily generates so that foreign substances such as dust and the like are absorbed on the alignment film. Rubbing the liquid crystal alignment film consequently decreases the yield and the productivity of the liquid crystal display module by requiring a separate washing process after rubbing.
Moreover, rubbing causes defects in the liquid crystal display device by generating a linear spot according to the rubbing direction of the rubbing fabric during the rubbing process. Also, light leakage arises from non-uniformities of the alignment at the step region of the substrate and the like. As a result, there is a need for technologies that eliminate the rubbing required to induce alignment.